Centrifugal mechanism

ABSTRACT

A centrifugal mechanism, for an internal combustion engine ignition distributor, includes a driven shaft and a cam shaft coupled to the driven shaft and having its axis coextensive with the driven shaft axis. Secured to the cam shaft is a first plate, and secured to the driven shaft is a second plate generally parallel with the first plate. A control weight is pivotally mounted on the second plate for movement about an axis parallel to the axis of the driven shaft and the control weight engages a cam carried by the first plate. Positioned between the first and second plates is a moulded synthetic resin spacer which maintains the first and second plates spaced apart by predetermined distance. In addition, the spacer is engaged by the control weight in the rest position of the weight.

Groom 1 Aug. 13, 1974 CENTRIFUGAL MECHANISM [75] inventor: Walter JosephGroom, Sutton Coldfield, England [73] Assignee: Joseph Lucus(Electrical) Limited,

Birmingham, England 22 Filed: Jan. 15, 1973 21 Appl. No.: 323,531

[30] Foreign Application Priority Data Jan. 15. 1972 Great Britain2021/72 [52] US. Cl. 64/25, 123/139 AP, 123/1465 [51] Int. Cl. Fl6d 5/00[58] Field of Search 64/25; 123/1465, 139 AP [56] References CitedUNITED STATES PATENTS 2,009,935 7/1935 Malbry 64/25 2,060,556 11/1936 1Davis, Jr. 64/25 3,045,458 7/1962 Campbell et al 64/25 25 let PrimaryExaminer-Samuel Scott Assistant Examiner-Randall Heald Attorney, Agent,or Firm-Holman & Stern [5 7] ABSTRACT A centrifugal mechanism, for aninternal combustion engine ignition distributor, includes a driven shaftand a cam shaft coupled to the driven shaft and having its axiscoextensive with the driven shaft axis. Secured to the cam shaft is afirst plate, and secured to the driven shaft is a second plate generallyparallel with the first plate. A control weight is pivotally mounted onthe second plate for movement about an axis parallel to the axis of thedriven shaft and the control weight engages a cam carried by the firstplate. Positioned between the first and second plates is a mouldedsynthetic resin spacer which maintains the first and second platesspaced apart bypredetermined distance. In addition, the spacer isengaged by the control weight in the rest position of the weight.

2 Claims, 4 Drawing Figures PATENTED 31374 3.828.57'9

SHEET 1 BF 2 I CENTRIFUGAL MECHANISM This invention relates to acentrifugal mechanism for an internal combustion engine ignitiondistributor.

A centrifugal mechanism according to the invention includes, a drivenshaft, a cam shaft, the cam shaft beingcoupled to the driven shaft andhaving its axis coextensive with the driven shaft axis, a first platesecured to the cam shaft, a second plate secured to the driven shaft andgenerally parallel with the first plate, a control weight pivotallymounted on one of the pair of plates constituted by the first plate andthe second plate, for movement about an axis generally parallel to thedriven shaft axis, a cam engaged by the control weight and carried bythe other plate of said pair of plates, and, a moulded syntheticresinspacer maintaining the first and second plates spaced apart by apredetermined amount, thespacer also being engaged by the control weightin a rest position of the weight.

Preferably the mechanism includes a second control weightand a secondcam engaged by the second control weight, the first and second controlweights being positioned diametrically opposite one another on oppositesides ofthe driven shaft axis and both control weights engaging thespacer in their rest position.

One example of the invention is illustrated in the accompanying drawingswherein:

FIG. 1 is a sectional view of a centrifugal mechanism for an internalcombustion engine ignition distributor,

FlG. 2 is a plan view of a spacer shown in section in FIG. 1, but to anenlarged scale,

FIG. 3 is a sectional view on the line 33 in FIG. 2, and,

FIG. 4 is a plan view illustrating the rest position of the controlweights of the centrifugal mechanism in relation to the spacer. 1

Referring to the drawings, the centrifugal mechanism in relation to thespacer.

Referring to the drawings, the centrifugal mechanism includes a drivenshaft 11 having a portion 11a of reduccd diameter. The driven shaft 11is in use journalled in the casing of the ignition distributor anddriven by the internal combustion engine utilizing the distributorsecured to the driven shaft 11 at the junction of the portion lla withthe remainder of the shaft is a plate 12 the plate 12 extendingtransversely with respect-to the axis of the shaft 11. Rotatably mountedon the portion 11a of the shaft 11 is a hollow cam shaft 13 having,intermediate its ends, a portion 13a which defines a cam, and which,inuse, is engaged by the cam follower of the contact breaker assembly ofthe ignition distributor. Secured to the end of the cam shaft 13adjacent the plate 12 is a plate 14 which extends transversely relativeto the axis of the cam shaft 13 and therefore extends parallel with theplate 12. Secured to the plate 14 by a pair of rivets '15 is a camplatel6. The rivets 15 secure the cam plate 16 to the plate 14 parallelthereto, and the plate 16 is formed with a centrally disposed aperturethrough which the portion 11a of the shaft 1.1extends. Upstanding fromthe plate 12 generally parallel with the axis of the shaft 11 are a pairof pivot posts 17. The pivot posts 17 are disposed diametricallyopposite one another on opposite sides of the axis of the shaft 11 andpivotally mounted on each of the posts 17 is a control weight 18. Thecontrol weights 18 are substantially identical with one another andextend between the planes of the plates 12 and 14. The control weights18 each include a short limb 19 and a longer limb 21 and are arrangedwith their longer limbs lying on opposite sides of the axis of the shaft11. As the shaft 11 is rotated then the weights 18 tend to pivot aboutthe posts 17 as their longer limbs 21 move outwardly under the action ofcentrifugal force. The cam plate 16 is provided adjacent its endsrespectively with a pair of cam surfaces 16a. The ends of the plate 16extend respec tively between the limbs of the two control weights andthe shorter limb 19 of each of the control weights includes a flatsurface 22 which engages the respective cam surface of the cam plate 16.Thus as the weights 18 pivot about the posts 17 the surfaces 22 rollaround their respective cam surface 16a and the cam surfaces are soshaped that the pivotal movement of the weights 18 moves the cam plate16 and therefore the plate 14 and the shaft 13 angularly relative to theshaft 11 about the axis of the shaft 11. The rivets 15 securing the camplate 16 to the plate 14 are extended, and project from the surface ofthe plate 14 remote from the plate 12 to define spring anchor posts 15a.A pair of tension springs 23 are provided for urging the assemblydefined by the cam shaft 13, the plate 14 and the plate 16 to a restposition relative to the driven shaft 11 and plate 12. Each of thetension springs 23 secured at one end to an anchor post 15a, and at itsother end to the adjacent pivot post 17. Thus the springs 23, togetherwith the weights 18 and the cam plate 16 inter-connect the 30 drivenshaft 11 and the cam shaft 13 so that the cam shaft 13 rotateswifh thedriven shaft 11, and additionally, as the mechanism rotates and theweights 18 pivot about the posts 17 then the cam shaft 13 is movedangularly relative to the driven shaft.

Positioned between the cam plate 16 and the plate 12 is a mouldedsynthetic resin spacer 24. The spacer 24 is annular and encircles theportion 11a of the shaft 11. At one axial end the spacer 24 abuts theplate 12, while at its other opposite end the spacer 24 abuts the plate16. Thus the spacer 24 serves to ensure that the plate 16, and thereforethe plate 14 are spaced by a predetermined distance from the plate 12.The thickness of the spacer 24 is chosen so that the control weights 18,which have a greater thickness than the cam plate 16 are not impededduring their pivotal movement by making facial contact with the plate14. The pivot posts 17 each include an integral collar spacing therespective control weight 18 from the plate 12. The spacer 24 which isshown diagrammatically in P10. 1, has a pair vide four peripheralrecesses 27.

The spacer engages the cam plate 16 with the cam plate entering betweenthe ribs 25 so that the ribs 25 provide a resilient abutment between thecontrol weights l8 and the cam plate. The cam plate extendsdiametrically from the confines of the spacer between an end of each ofthe ribs 25 and the adjacent post 26, abutment of the cam plate with theend of a rib 25 or a post 26 resisting angular movement of the spacerrelative to the cam plate, A space is left between the other end of eachrib and the adjacent post 26 so that the same spacer can be utilized ineither a clockwise or an anti-clockwise rotation mechanism, andsimilarly there are provided four rather than two recesses 27. Therecesses 27 are provided to ensure that the limbs 22 of the weights 18do not abut the spacer during pivoting movement of the weights.

The springs 23 urge the centrifugal mechanism to a rest position, and inthe rest position projections provided on the longer limbs 21 of thecontrol weights l8 engage the ribs 25 of the spacer 24. The dimensionsof the mechanism are such that the springs 23 urge the weights 18 intocontact with the spacer, and since the spacer is formed from syntheticresin material, and so has some inherent resilience, the mechanism isless inclined to rattle in use than would be a similar arrangement wherethe weights engage for example the steel shaft 11. As stated above thespacer spaces the cam plate 16 from the plate 12 and since the plate 16moves angularly in use relative to the plate 12 the spacer acts also asa bearing. Conveniently the spacer is formed in a material such as Nylonwhich has the properties required for the various tasks of the spacer.

I claim:

l. A centrifugal mechanism, foran ignition distributor, including adriven shaft, a cam shaft, the cam shaft being coupled to the drivenshaft and having its axis coextensive with the driven shaft axis, afirst plate secured to the cam shaft, a second plate secured to thedriven shaft and generally parallel with the first plate, a controlweight pivotally mounted on one of the pair of plates constituted by thefirst plate and the second plate, for movement about an axis generallyparallel to the driven shaft axis, a cam engaged by the control weightand carried by the other plate of said pair of plates, and, a mouldedsynthetic resin spacer maintaining the first and second plates spacedapart by a predetermined amount, the spacer also being engaged by thecontrol weight in a rest position of the weight.

2. A centrifugal mechanism as claimed in claim 1 further including asecond control weight and a second cam engaged by the second controlweight, the first and second control weights being positioneddiametrically opposite one another on opposite sides of the driven shaftaxis and both control weights engaging the spacer in their restposition.

1. A centrifugal mechanism, for an ignition distributor, including adriven shaft, a cam shaft, the cam shaft being coupled to the drivenshaft and having its axis co-extensive with the driven shaft axis, afirst plate secured to the cam shaft, a second plate secured to thedriven shaft and generally parallel with the first plate, a controlweight pivotally mounted on one of the pair of plates constituted by thefirst plate and the second plate, for movement about an axis generallyparallel to the driven shaft axis, a cam engaged by the control weightand carried by the other plate of said pair of plates, and, a mouldedsynthetic resin spacer maintaining the first and second plates spacedapart by a predetermined amount, the spacer also being engaged by thecontrol weight in a rest position of the weight.
 2. A centrifugalmechanism as claimed in claim 1 further including a second controlweight and a second cam engaged by the second control weight, the firstand second control weights being positioned diametrically opposite oneanother on opposite sides of the driven shaft axis and both controlweights engaging the spacer in their rest position.